Conventionally, an electric double-layer capacitor is employed as an electric capacitor with a large capacity and high energy in electric power applications and the like. Many of the electric double-layer capacitors include capacitor cells, in each of which a positive electrode and a negative electrode, and a separator interposed therebetween, are housed in an exterior case (for example, aluminum laminate case or the like) together with an electrolytic solution. The capacitor cell ordinarily has a configuration, in which a positive electrode terminal and a negative electrode terminal are drawn from a sealed section of the exterior case. Since an output voltage of a single capacitor cell itself is low that is around several volts (V), the capacitor cells are typically utilized as a capacitor module, in which terminals of a plurality of capacitor cells are connected according to a series connection, a parallel connection, or a series-parallel connection containing the series connection and the parallel connection coexisting therein, in order to obtain a desired output performance (for example, see Patent Literature 1).